1. Technical Field
The disclosure relates to heat dissipation devices, and particularly to a heat dissipation device having an improved fan assembly.
2. Description of Related Art
Electronic components operating at high speed generate excessive heat which must be removed efficiently to ensure normal operation. Typically, a heat dissipation device attached to the electronic component provides such heat dissipation.
For example, U.S. Pat. No. 6,311,766 provides such a heat dissipation device for dissipating heat generated by a CPU. The heat dissipation device includes a fan, a heat sink, and a fixing device which attaches the fan to the heat sink. The fan is box-shaped, and includes a rectangular housing, a hub received in a central portion of the housing and a plurality of blades extending radially from the hub. The hub includes a circular top wall and a cylindrical sidewall extending perpendicularly from an outer periphery of the top wall. The top wall and the sidewall define a cylindrical space for accommodating a magnet and a stator therein for driving the blades to rotate in the housing. Typically, the stator includes layered yokes with stator coils wound thereon, a printed circuit board (PCB) electrically connected with the stator coils, and upper and lower insulating frames insulated the layered yokes from the stator coils. Thus, the stator has a large size, and a large space for accommodating the stator is accordingly needed, which increases a size of the hub.
When the fan operates, the top wall of the hub prevents air from flowing into an area just under the top wall, so that the area just under the top wall lacks airflow and forms as an airflow dead area to cause heat to accumulate there. The size of the hub is large, and a size of the airflow dead area is large accordingly. Thus, an efficiency of the cooling fan is greatly affected.
It is thus desirable to provide a heat dissipation device which can overcome the described limitations.